Relating to or affecting the crissum (the area around the cloaca in birds and some other animals).
From 'crissum' (the anatomical region) plus the adjective-forming suffix '-al.' It's used in ornithological and anatomical scientific terminology.
Scientific adjectives like 'crissal' exist in a special vocabulary reserved for experts—which is why they sound strange to most people but are beautifully precise to ornithologists discussing bird feather patterns.
Complete word intelligence in one call. Free tier — 50 lookups/day.